Control



Nov. 8, 1938. w. J. MCGOLDRICK 2,135,829

CONTROL Filed Aug. 17, 1936 4 Sheets-Sheet 1 RELAY I 4/ RESETBUITON nun;BURNER MOTOR Pan/ER 97 LI/YE' BURNER IGNITION WM IMcW m I Nov. 8, 1938.w. J. McGOLDRICK CONTROL 4 Sheets-Sheet 2 Filed Aug. 17, 1936 FIG.5.

T m m T 6 m N fi O L w .3 0 U (7 m m a w w W N r\ 0 m w 6 6 W /r 4 fifif3 E 5 W H w 4 I- I4 N 5 m as K w w m 3 PI 17 r. m a M Lab 5 w Nov. 8,1938. w. J. MCGOLDRICK 2,135,829

CONTROL Filed Aug. 17, 1956 4 Sheets-Sheet 4 6 RELAY COMBUSTION CONTROLROOM THERMOSTAT a l I 5 63 w 5/49 V {46 I 9/ I 94 A L r P a? *89 6/BURNER MOTOR 97 Powm LINE BURNER IGNITION 88 Patented Nov. 8, 1938PATENT OFFICE CONTROL William J.- McGoldrick, Marshfleld, Mass,assignor, by mesne assignments, to Metals 8; Controls Corporation,Attleboro, Mass, a corporation of Massachusetts Application August r2,1936, Serial No. 96,446

16 Claims.

This invention relates to controls, and with regard to certain morespecific features, to a control means together with a circuit embodyingthe same, for motor-driven oil burners.

Among the several objects of the invention may be noted the provision ofa control for motordriven oil burners, and a circuit therefor, whichprovides automatically for a period of trial operation, thereafterfunctioning to continue operation of the motor if combustion issuccessful, but discontinuing operation of the motor if combustion isunsuccessful, and, in the latter instance, automatically setting up alocked condition in which a manual operation is necessary in order torestore the control to automatic functioning;

and the provision of a control and circuit therefor of the classdescribed which is equipped to handle automatically substantially anyfailure or the like that is encountered in normal or O abnormaloperation of a motor-driven oil burner.

embodying said control;

Fig. 2 is a cross section taken substantially along line 2-2 of Fig. 1;

Fig. 3 is a. cross section taken substantially along line 3-4 of Fig. 1;

Fig. 4 is a cross section taken substantially along line 4-4 of Fig. 1;and,

Figures 5, 6, and 7 are diagrammatic views similar to Fig. 1;illustrating alternative positions in the operations of the control ofthe present invention.

Similar reference characters indicate correspondingparts throughout theseveral views of .the drawings.

The present invention discloses a novel means of automatically startingmotor-driven oil burner systems, and automatically preventing acontinuation of starting attempts when operation is undesirable.

In automatically starting systems of this type, for example, the usualsequence of events which are cycled by such control means are:

2. Starting of oil burner motor on trial basis. 7

3. Turning on ignitor.

4. Detecting combustion.

5. Turning ofi? ignitor when combustion is assured (optional).

.6. Continuing operation of oil burner motor as long as there iscombustion and demand.

7. When demand is satisfied, shutting down burner and preparing forrepetition of the above events 'on renewal of the demand for heat.

In motor driven oil burning systems, certain events in themselves or bya combination of their separate effects may make it advisable tointerrupt starting and make further attempts at starting impossibleuntil the cause of trouble is determined and remedied. .In such casesthe control means should cause the system to shut down, and shouldremain locked out until the trouble is corrected, after which thecontrol means should, upon being reset manually, function in its regularfashion.

Events, for example, such as power supply failure, fuel faflure,ignition failure, or flame failure, should cause the control means toact as, a safety device on a false start. Power failure, for instance,may be a matter of complete loss of power, or it may be only a momentaryor intermittent interruption. Again, it might be in the form of a dropin line voltage, causing inadequate fuel turbulence with attendantdecrease in combustion efilciency, conceivably resulting in the loadingof the combustion chamber with inflammable but unburned liquids in thepresence of an'open flame. It is possible that under this condition suchunburned liquid fuel might be heatedto the point of vaporization andignite, some of it flowing outside the base of the burner while aflame.

,The matter of fuel failure may likewise be complete, due to theconsumption o1 the supply, or partial, due to the clogging of the feedline or nozzle, or breakdown of the pump supplying it.

In the case .of ignition failure, common control meansallowseveralstarting attempts when ignition is not first successful. 9While it is true that a short time interval elapses between each of suchtrials, it is maintained that only one attempt should be made. I'his isbecause motor-driven oil burners are commonly designed to supply fuelunderpressure in a finely subdivided state and intimately mixed with aturbulent stream of air. If ignition does not occur on starting, themixture escapes into the stack and chimney where it mingles with otherair and presents an explosion hazard, if a subsequent attempt atignition following soon after is successful.

Hence, a control means which locks out on the first failure of ignitionis preferable in that it allows a purging period of a duration subjectto the judgment of manual aid.

Flame failure may occur as a result of impurities, such as water,getting into the fuel or because of motor burnouts or bearing seizure.

In any of the events, such as are described above, a motor-driven oilburner control means should preferably cause a full shutdown of thesystem, pending manual restoration of operation.

The present invention provides a control means including both a deviceand the circuit for operating said device, which supplies all of theneeds as expressed above.

Referring now more particularly to Fig. 1, numeral 1 indicates a controlmeans or relay, which is the principal control of the present invention.The circuit connections of the control means I are likewise shown andwill be described hereinafter. However, it is considered advisable firstto describe the control means I, in detail.

Numeral 2 indicates a base plate upon which the control means ismounted. Near the top of the base plate 2 there is provided apermanently mounted electromagnet 3, which has windings 4 and a core 5.A bracket 6, which is mounted on the base plate 2, supports the core 5.

Numeral '1' (see also Fig. 3) indicates a second bracket mounted on thebase plate 2, in position beneath the electromagnet 3. Bracket 1 has aforward pointed. or triangular section 8, the three corners 9 of whichsupport downwardly extending posts 10. Near their lower ends, the postsID are provided with peripheral grooves H, which receive, in anon-binding manner, the flat periphery l2 of a radially corrugatedsnap-acting thermostatic disc I3. The disc I3 is of the type shown anddescribed in John A. Spencer Patent No. 1,895,591, dated January 31,1933. The disc [3 has a central opening l4.

A characteristic of the disc l3-is that it is formed initially so thatit is slightly concave in one direction. Fig. 1 shows a downwardconcavity, for example. This downward concavity of Fig. 1 corresponds torelatively cold ambient temperatures. When the ambient temperature risesabove a predetermined value, the thermostatic disc l3, by reason of itsconstruction, will snap upwardly into an upwardly concave or hotposition such as that shown in Fig. 5, for example. For a more detaileddiscussion of the operation of thethermostatic disc l3, reference isdirected to the aforesaid Spencer Patent 1,895,591.

Referring again to Fig. l, numeral l5 indicates a hub or like elementwhich slides freely in the central opening l4 of the disc 13. The hub 15has an outwardly extending annular flange I5 at its upper end. It isinteriorly drilled and threaded to receive a stem [1, which is ofconsiderable length.

The upper face of bracket 1 is provided with a pair of circularprojections l8 and I9, which are of decreasing diameter, providinglateral steps or shoulders or abutments, for purposes to be describedhereinafter. Under the projection IS the bracket 1 is provided with arecess indicated by numeral 28. The projection 13 is centrally drilledto receive, in a sliding manner, a collar 2| which is threaded on thestem H. The collar 2] carries an outwardly extending flange 22 at itsupper end. A compression spring 23 reacts between the base of the recess20 and the top of the hub I5.

Threaded to the upper end of the stem I1 is an armature or pole piece 24(see also Fig. 2). At its sides, the armature 24 is provided with slots25. The armature 24 comprises a magnetic metal such as iron. Its lowerface, however, is preferably covered with a non-magnetic metallic sheet21, which may be brass, for example. The ends of the sheet 21 are bentupwardly to embrace the front and back faces of the armature 24, and aresecured thereto as by rivets or the like 28.

The sheet 21 is provided, in the regions beneath each of the slots 25,with pairs of sidewardly extending projections 29, each two of whichreceive and support a pivot pin 30. The pivot pins 30 serve to supportrotatable latches 3|, which preferably each comprise a single piecehaving an upward projection 32 adapted to slide into a slot 25, adownward projection 33, and a nose 34 positioned to abut the plate orsheet 21 on the under surface of the armature 24. The single piececomprising the portions 31, 32, 33, and 34 is preferably made of brassor some similar non-magnetic material. To the side of the portion 32 iswelded, soldered, or otherwise secured a small magnetic piece 35, whichmay be iron, steel or the like. The piece 35 is sufliciently wide toextend entirely across the end of its slot 25 and, in a closed positionto be described, abut the end face of the armature 24.

The shape and arrangements of the latches 3| is such that, when nomagnetic forces are being applied, gravity will cause the latches torotate outwardly until the noses 34 engage the under side of thearmature 24. This is the position illustrated, for example, in Fig. 5.In this position, the ends of the portions 33 of the latches 3| arecloser together than the diameter of the portion I8 of bracket 1, asshown in Fig. 5. However, when magnetic forces are present ashereinafter described, the pieces 35 are drawn to the armature 24,rotating the latches 3| to the position shown in Fig. 1, in which thelower edges of portions 33 are spaced sufliciently far apart to permitthem to slip down over the projection I8 on bracket 1. The latchets 3|may thus be described as gravitationally responsive in one direction andmagnetically responsive in the other direction. 1

A pair of pins 36 are mounted in the upper face of the armature 24 andextend upwardly into suitable openings in the pole 5 of theelectromagnet 3, to prevent relative rotation of the armature 24 and thecore 5.

Numeral 31 indicates an electrical resistance heating element (see alsoFig. 3) which is mounted on a plate 33, preferably resistant to heat andelectrically resistant, which in turn is mounted by posts 10 on theunder side of the bracket 1. The ends of the coil 31 are connected tobinding posts 39 and 40, respectively/on the plate 33. The coil 37 ispositioned to heat the thermostatic disc 13 for reasons to be describedhereinafter. The circuit connections to the coil 31 will also bedescribed hereinafter,

Numeral 42 indicfit? an insulating material bracket which likewise ismounted on the base plate 2, some distance below the bracket 1. At oneend of the bracket 42, there is mounted a post or pillar 43, whichserves to support two parallel leaf-spring contact arms 44 and 45, re-

spectively. The contact-arm 44 carries a mov- 75 2,185,829 able contact46 at its end which cooperates with a suitably mounted fixed contact 41.The arm 44 and contacts 46 and 41 thus constitute a single pole, singlethrow switch. The stem passes through the center of arm 44, and aninsulating washer 48 is interposed between the lower edge of hub i andarm 44.

The free end of contact arm 45 carries a double -faced movable contact49, which upwardly cooperates with a fixed contact 56, and alternativelydownwardly cooperates with a fixed contact 5!. The assembly comprisesthe'arm 45, and the contacts 49, 56 and 5|, thus constitutes a singlepole, double throw switch. The lower end of stem |1 mounts a pin 52,preferably of insulating material, which bears upon the upper surface ofthe middle portion of arm 45. A some what larger pin 53 of insulatingmaterial, which slides in a suitable opening in the bracket 423sdisposed axially beneath the pin 52, and abuts the under surface of thespring arm 45.

On the under side of the bracket piece 42 there is mounted, at theleft-hand end of the bracket 42, a third spring contact arm 54, againstwhich the lower end of pin 53 bears. .The free end oi arm 54 is providedwith a movable contact 55, which cooperates with a stationary contact 56mounted on the lower face of the bracket 42. The free end of the arm 54is at the opposite end of the bracket 42 from the end of arms 44 and 45,in order to provide a balanced thrust. The" assembly comprising the arm54 and contacts 55 and 56, constitutes a single pole, single throwswitch, as will be seen.

All three of the contact arms 44, 45, and 54 are initially tensioned sothat they tend to return to their upward position. This means that thecontact arm 44 normally tends to juxtapose the contacts 46 and 41; thecontact arm 45 normally tends to iuxtapose the contacts 49 and 58; andthe contact arm 54 normally tends to juxtapose the contacts 55 and 56'This is the position shown, for example, in Fig. 5.

The foregoing completes the description of the relay or control unit l,forming part of the present invention. The circuit connections of saidcontrol unit will now be described.

Numerals GI and 62 indicate the wires of a main power line or circuit,such as a 1l0-volt A. C. A low'voltage transformer 63 is provided, theprimary 64 of which is connected across the power circuit 6|62. One side65 of the secondary 66 of the transformer 63 is connected to a roomthermostat 61 of customary construction, the other contact of which isconnected by a wire 68 to a combustion control device 69, whichcomprises a thermostatic blade or the like 18 adapted to move between acold position and a hot position. Theblade 18 constitutes the movablecontact of a single pole, double throw switch, and is connected directlyto the wire68. In its cold position, the. contact at the end of arm 18connects with a stationary contact 1| while in it's hot position, itconnects with a stationary contact 12. The combustion control 69 as thusdescribed, is exemplary only, it being necessary merely to provide athermostatically controlled, single pole, double throw switch, in whichone position corresponds to a cold position, and the other positioncorresponds to a hot position. The cold contact 1| is connected by awire I12 to the terminal 89 of the electric resistance heating coil 31,while the other terminal 48 of the coil 31 is connected by a wire 13 tothe lower stationary to the other power line 6|.

contact 5| which cooperates with the spring arm 45 of the relay I.

The hot contact 12 of the combustion control 69 is connected by a wire14 to one end of the winding 4 of the electromagnet 5. The other end ofthe winding 4 of the electromagnet 3 is connected by a wire to the uppercontact 58 cooperating with the spring contact arm 45 of the relay i.

Numeral 16 indicates a manually operated switching device which is usedin connection with comprises a double pole, single throw switch arrangedfor coextensive movement. For example,

a pair of contacts 11 and 18 are provided which are brldgeable by aswitching contact arm 19, and a second pair of contacts 89 and 8| areprovided which are bridgeable by a contact arm 82. A compression spring63 normally maintains both the bars 19 and 82 disconnected from theirrespective contacts, but by manually depressing a button 84, the contactarm 19 may be made to connect the contacts 11 and 18 while at the sametime, the contact arm connects the contacts 85 and 8|, The contact 11 isconnected by a wire I83 to wire 65 leading from the transformersecondary 65 to the room thermostat 6t. The contact 18 is connected by awire 59 to the wire 14 leading from the hot contact 12 of combus tioncontrol 65. The contact 8! is connected by a wire 85 to the wire 15leading from the electromagnet winding 4 to the contact 56. The con-'tact 89 is connected by a wire 86 to the other terminal of the secondary66 of the transformer 63. This terminal of the secondary is likewiseconnected, by a wire 81, to the movable contact the present invention.The switching device 16 arm 45 of the control device i, which'connectsalternately with contacts 58 and 59.

Numeral 88 indicates the motor of the burner which it is desired tocontrol. One side of the burner motor 86 is connected by a wire 89 toone side 62 of the power circuit. The other side of the motor 88 isconnected by a wire 98 to the switch arm 54. The contact 56 cooperatingwith the switch arm 54 is connected by a wire 9| to the other powercircuit line 6|. Numeral 92 indicates a parallel connection from thepower wire 89 leading to the motor, 88, which runs to one terminal of aprimary 93 of a burner ignition transformer 94. The other terminal ofthe primary 83 is connected by a wire 95 to the stationary switchcontact 41 of the control device 5. The switch arm 44 cooperating withthe contact 41 is connected by a wire 96 to the wire 9| in the burnermotor circuit, which is in turn connected Thus, the primary 93 of theburner ignition transformer 94 is connected in parallel with the burnermotor 88. The secondary 91 of the burner ignition transformer 92 isconnected in a suitable manner to the burner ignition means, which isnot shown.

The above completes the description of the circuit employed with thecontrol of the present invention. The operation of the control .circuitwill now be described.

Fig. 1 is considered as showing the control device in its normal 01!position, coil spring 23 69 is in its cold position. For purposes of de-75 scription, it will be assumed that the room thermostat has justclosed, and that a call for heat has just been made, in order to eifecta start of the oil burner.

Tracing the circuit through the room thermostat 61, it will be seen thatthe heating coil 31 is now energized and is radiating heat to thethermostatic disc l3, It should be noted here that if the heating coil31 should burn out, the disc i3 would receive no heat and starting wouldthus be prevented.

Disc l3 eventually becomes heated to a degree which causes it to snapupwards to the position shown in Fig. 5. This allows switch arms 44, 45,and 54, respectively, to close circuits through their respective fixedcontacts 41, 50 and 56; while at the same time it causes latches 3| tomove inwardly, by gravity, over circular projection l8 and armature 24to be lifted upward toward the core 5 of electromagnet 3.

Tracing the various circuits thus closed (as shown in Fig. 5), it willbe seen that the ignition transformer 94 is energized through contact41; the electromagnet circuit will be closed on one side through contact50; and the oil burner motor circuit closed through contact 56. Fromthis point on, two courses of events are possible: namely, (1) ignitionis successful and combustion begins; or (2) ignition is not successfuland there is no combustion. These will be dealt with separately butbefore going into this discussion it should be noted that a novel meansof timing the trial period of starting the oil burner is effected. I

Whereas common motor driven oil burner control means depend upon theperiod of heating of a thermostatic element as a trial operation timelimit, the present control means depends upon the period of cooling ofthe thermostatic element. This novelty is a considerable improvement; inthe art, in that ambient temperatures which cause the cooling of thethermostatic element l3 of the present invention are much more uniformin places of oil burner location, such as the basement of houses, thanare the line voltages which cause heating of thermal elements in commoncontrol means. Consequently, greater accuracy in limiting the trialperiod is achieved, which is important when it is remembered that thepurpose of the control means is to regulate a series of events whichhave a definite time relation to each other.

Returning to the two possibilities depending upon the success ofcombustion, in the first case, if ignition is successful and goodcombustion is assured, the switch arm 10 of the combustion control 69then moves over to the hot contact 12 within the cooling period of thedisc l3, and closes the other side of the electromagnet circuit. As theelectromagnet 3 is now energized and the armature 24 has been previouslymoved and held within magnetically responsive distance of the core 5 bythe upward snap of the thermostatic disc I3, the armature 24 isattracted to and held in place by core 5. Thereafter, as long as thereis good combustion, and demand by the room thermostat 61 continues,armature 24 allows switch arms 44, 45 and 54 to remain in "on" position,and the oil burner continues to operate.

In addition, latches 3| are moved outwardly away from projection 48 byresponse to magnetic attraction of the pole piece 24 upon the pieces 35.

Since the upward snap of disc 13 has broken the circuit supplying theheater coil 31. the

disc l3 begins to cool off, and ultimately, when it cools suiiiciently,it snaps downwardly to resume its original position where it remainsready to repeat the starting cycle again on the next demand.

The position of the elements at this stage is as shown in Fig. 6.

Considering now the second case hinging on combustion; that is, failureof ignition. When this occurs, the switch arm III of the combustioncontrol 69 fails to move over to the hot contact I2. Hence, there is noenergization of the electromagnet 3 and no magnetic attraction of thearmature 24 or latches 3|. In due time, therefore, when the thermostaticelement i3 cools to the snapping point in a downward direction, latches3| will come to rest on the top of projection l8, thus holding switcharms 44 and 54 away from contacts 41 and 56, and holding switch arm 45midway between contacts 50 and BI. All

control circuits to the burner motor 88 are thus' locked open, andfurther operation is not powble until the control means is manuallyreset. Fig. 7 shows the positions of the several elements at this stage.

Manual resetting is provided by the'manual reset switch 16. It will benoted that closing of this switch by pushing the button 34 thereofresults in the energization of electromagnet 3 which will then lift thearmature 24 from its suspended position and magnetically cause latches3| to move outwardly away from the projection 13. Release of the button34 then opens the circuit and permits the armature 24 to drop back toits normal "off" position before latches 3| can again come to rest onprojection II by gravitational movement. From this point on, assumingthat the cause of ignition failure has been corrected, the control meanswill now function normally in the manner already described.

To review some of the events which make'it desirable for the oil burnermotor 33 to be shut down and the control device I to be locked out ifstarting is undesirable, 'the following may be mentioned.

1. Power supply failure in power lines il-fl.

A. Momentary or intermittent interruption.

If the electromagnet 3 is de-ienergimd during starting, that is, beforedisc I3 returns to its downward position, pole piece 24 drops tosuspended Fig. 7 position and, held by latches 3|. breaks theelectromagnet circuit through contact 50, thus locking out the controldevice I.

If electromagnet 3 is de-energized during running, pole piece 24 dropsto starting position, and heating coil 31 must be suiilclently energizedbefore another start can be effected.

- B. Voltage drop.

The electromagnet 3 is designed to fail to hold pole piece 24 and movelatches 3| when voltage drops below point for maintenance of goodcombustion, thus looking out the control device I as in A above.

2. Fuel failure at oil burner.

A. Complete failure.

As there will be no combustion, combustion control 69 fails to reach"hot contact 12, and thus electromagnet 3 is not energized and controldevice I looks out;

B. Partial failure.

When combustion receives insuflicient fuel to maintain flame and keepcombustion control 33 on-hot contact 12, electromagnet 3 is deenergized,pole piece 24 drops to starting posiunsuccessful.

3. Ignition failure.

Action as already described.

4. Flame failure.

Action as described under paragraph 2, section B, above;

In the event of complete or relatively permanent power failure in powerlines 6l--62, the heating coil 31 receives no current in any event, andhence there is no attempt at starting.

While the system as shown in the diagram and as described thus farcovers what might be called a low-voltage system with continuous orrunning ignition, modifications of the system are possible to coversystems using line voltage, or systems with intermittent or startingignition only.

In some heaters the flame burns at a distance from the point of exit offuel mixture from the burner nozzle. In others the flame may issuedirectly from the nozzle; hence, there is a difference of opinion as towhether the ignition should cut off or should continue after combustionis assured. It is obvious that .with simple modifications of the presentcontrol means,

either is possible.

It is only necessary to insert another switch in the circuit throughcontact arm 44, for example, which switch would be magneticallyresponsive to electromagnet 3. This additional switch would break thecircuit to the ignition transformer 93 when the combustion control 69reached its hot" contact 12 and electromagnet 3 is energized.

In the matter of line voltage operation, it is only necessary to adaptthe heating coil 31, electromagnet 3, combustion control 69, and roomthermostat 61 to line voltage use to achieve identical performance. Inthis instance intermittent or starting ignition can be arranged,

by connecting switch arm 44 to the cold contact ll instead of aspreviously described, if preferable. As combustion (hence, ignition)must take place before the combustion control switch arm 10 moves awayfrom its cold contact II, this means of shutting off ignition ispractical.

It should be noted that when the windings 3 of the electromagnet 4 areenergized, a magnetic field is set up within and around the core 5. Thismagnetic field attracts armature 24 but intentionally with insufflcientpower in itself to lift the armature 24 from its ofi or Fig. 1 position.v

In view of the above, it will be seen that the several objects of theinvention are achieved and other advantageous results attained.

As many changes could be made in carrying out the above constructionswithout departing from the scope of the invention, it is intended thatall matter contained in the above description or shown in theaccompanying drawings shall be interpreted-as illustrative and not in alimiting sense.

I claim:

1. A control device comprising an electromagnet, a --movable armature,actuating means for said armature capable of moving said armaturealternatively to a first position in which it is magnetically responsiveto said electromagnet and to a second position in which it ismagnetically relatively non-responsive to said electromagnet, latchingmeans mounted on said armature, and abutment means normally cooperatingwith said latching means to hold said armature in a third positionbetween said first and second positions when said armature tends to movefrom its first to its second position, said latching means beingresponsive to magnetism in said armature by movement to a position inwhich no cooperationwithysaid abutment means is had,

and control-electing means mechanically connected to said armature insuch manner that the position of the armature determines the position ofthe control-effecting means.

2. A control device comprising an electromagnet, a movable armature,actuating means for said armature capable of moving said armaturealternatively to a first position in which it is magnetically responsiveto said electromagnet and to a second position in which it ismagnetically relatively non-responsive to said electromagnet, latchingmeans mounted on said armature, and abutment means normally cooperatingwith said latching means to hold said armature in a thirdposition-between said first and second positions when said armaturetends to move from its first to its @econd position, said latching meansbeing responsive to magnetism in said armature by movement to a positionin which no cooperation withsaid abutment means is had, and electricswitching means mechanically connected to said armature in such mannerthat the position of the armature determines the position of theswitching means.

'3. A control device as set forth in claim 1, in which the actuatingmeans comprises thermostatic means having a hot position and a coldposition, and electrical heating means controlling the temperature ofsaid thermostatic means.

4. A control device as set forth in claim 2, in which the actuatingmeans comprises thermostatic means having a hot position and a coldposition, and electrical heating means controlling the temperature ofsaid thermostatic means.

5. A control device as set forth in claim 2, in which the actuatingmeans comprises thermostatic means having a hot position and a coldposition, and electrical heating means controlling the temperature ofsaid thermostatic means, and in which the electric heating means is in acircuit including at least one of the switching means, which switchingmeans is arranged to interrupt the flow of current to said heating meanswhen the aforesaid thermostatic means assumes its hot position.

6. A control device as set forth in claim 1, in which the actuatingmeans comprises thermostatic means having a hot position and a coldposition, and electrical heating means controlling the temperature ofsaid thermostatic means, said armature being positioned in its aforesaidfirst position when said thermostatic means is in its hot position.

7. A control device comprising an electromagnet, an armature composed ofmaterial which is magnetically responsive, mounting means for saidarmature permitting it to move to and from said electromagnet, separatemeans for moving said armature, independently of said electromagnet,into a first position in which the armature is too far distant from saidelectromagnet to move in response to electrical actuation thereof, andalternatively into ,a second position in which the armature issufficiently close to the electromagnet to move and be held thereto inresponse to electrical actuation thereof, abutment means associated withsaid mounting means, and at least one latching means movably mounted onsaid armature, said latching means having at least a part thereofcomposed of material which is magnetically responsive whereby, upon theestablishment of a suficient magnetic flux in said armature by reason ofits juxtaposition to the electrically actuated electromagnet, saidlatching means is forced into a position in which it does not cooperatewith said abutment means, said latching means otherwise assuming aposition in which it cooperates with the abutment means in such manneras to hold the said armature from returning to its aforesaid firstposition.

8. A control device comprising a circuit-controlling electrical switchhaving a movable contact, an element mechanically coupled to saidmovable contact for actuating the same, a thermostat having relativelyhot and cold positions, an electrical heater for heating said thermostatto cause it to move to its hot position, said heater being connected toa source of current through said switch, means coupling said thermostatand said element in such manner that as said thermostat moves to its hotposition, said element opens said switch, and holds it open as long assaid thermostat remains in its hot position, an armature mechanicallycoupled to said element, and an electromagnet positioned so that when itis energized, and when said thermostat is in its hot position, saidarmature is magnetically held to said electromagnet in such manner thatsaid element maintains said switch in open position, said element, inthe event of absence of energization of said electromagnet and return ofsaid thermostat to its cold position, tending to return said switch toits closed position, relatively stationary abutment means, and latchingmeans on said armature cooperating with said abutment means to preventsaid element from closing said switch when said electromagnet is notenergized and said thermostat moves from its hot to its cold position.

9. A control device comprising a circuit-controlling electrical switchhaving a movable contact, an element mechanically coupled to saidmovable contact for actuating the same, a thermostat having relativelyhot and cold positions, an electrical heater for heating said thermostatto cause it to move to its hot position, said heater being connected toa source of current through said switch, means coupling said thermostatand said element in such manner that as said thermostat moves to its hotposition, said element opens said switch, and holds it open as long assaid thermostat remains in its hot position, an armature mechanicallycoupled to said element, and an electromagnet positioned so that when itis energized, and when said thermostat is in its hot position, saidarmature is magnetically held to said electromagnet in such manner thatsaid element maintains said switch in open position, said element,in'the event of absence of energization of said electromagnet and returnof said thermostat to its cold position, tending to return said switchto its closed position, relatively stationary abutment means, andlatching means on said armature cooperating with said abutment means toprevent said element from closing said switch when said electromagnet isnot energized and said thermostat moves from its hot to its coldposition, said latching means being composed at least in part ofmagnetically responsive material and thereby being magneticallyresponsive to magnetic flux in said armature induced by the energizedelectromagnet, whereby said latching means are rendered non-cooperativewith said abutment means when said electromagnet is energized.

10. A control device comprising a circuit-controlling electrical switchhaving a movable contact, an element mechanically coupled to saidmovable contact for actuating the same, a thermostat having relativelyhot and cold positions, an electrical heater for heating said thermostatto cause it to move to its hot position, said heater being connected toasource of current through said switch, means coupling said thermostatand said element in such manner that as said thermostat moves to its hotposition, said element opens said switch, and holds it open as long assaid thermostat remains in its hot position, an armature mechanicallycoupled to said element, and an electromagnet positioned so that when itis energized, and when said thermostat is in its hot position, saidarmature is magnetically held to said electromagnet in such manner thatsaid element maintains said switch in open position, said element, inthe event of absence of energizetion of said electromagnet and return ofsaid thermostat to its cold position, tending to return said switch toits closed position, relatively stationary abutment means, and latchingmeans on said armature cooperating with said abutment means to preventsaid element from closing said 'switch when said electromagnet is notenergized and said thermostat moves from its hot to its cold position,and a second electrical switch having a movable contact likewisemechanically coupled to said element for movement therewith, said secondelectrical switch being moved by said element from a first into a secondpredetermined circuit-controlling position when said thermostat moves toits hot position and being maintained thereafter in said secondpredetermined position for a period of time at least as long as saidthermostat takes to cool sufiiciently to move to its cold position,energization of said electromagnet during the interval while saidthermostat is in its hot position causing said second switch to bemaintained in said second predetermined position regardless ofsubsequent movements of said thermostat, but absence of energization ofsaid electromagnet during the interval while said thermostat is in itshot position causing said second switch to be returned to its firstpredetermined position as said thermostat moves to its cold position.

11. A burner control system comprising an oil burner motor, a powercircuit including said motor and an electrical switch in said power circuit having a movable contact; a control circuit including a source ofpower, a room thermostat which closes upon demand for heat connected inseries therewith, a combustion control in series with the roomthermostat, which combustion control closes a first branch circuit uponattainment of satisfactory combustion at the oil burner and which closesa second branch circuit when satisfactory combustion is not taking placeat the oil burner, said first branch circuit including an electricalheater and said second branch circuit including an electromagnet, thereturn lead of the heater being connected to one stationary contact of asingle-pole double-throw electrical switch while the return lead of theelectromagnet is connected to the other stationary contact of saidsingle-pole double-throw switch, the movable contact of said single-poledouble-throw switch being connected to the aforesaid control circuitpower source; an element mechanically coupled to the movable contacts ofboth said burner motor switch and said single-pole doublethrow switchior'actuating the same, a thermostat having relatively hot and coldpositions and located in such manner as to be heated by the aforesaidelectrical heater and thereby be caused to move to its hot position,means mechanically coupling said thermostat and said element in suchmanner that as said thermostat moves to its hot position, it actuatessaid element to close said burner motor switch to empower the burnermotor and to move the movable contact of the single-pole double-throwswitch from the stationary contact of the aforesaid first branch circuitto the stationary contact of the aforesaid second branch circuit,thereby to deenergize the electrical heater and to place theelectromagnet in condition to be energized, said thermostat thereuponcommencing to cool, an armature mechanically coupled to said element andpositioned to be magnetically responsive to the aforesaid eiectromagnetwhen said electromagnet is energized and when said armature is-in aposition corresponding to the hot position of said thermostat, saidelectromagnet normally being energized during the interval that saidthermostat is in its hot position by said combustion control moving toclose the aforesaid second branch circult, said electromagnet during itsenergization thereby maintaining said element in a switchcontrollingposition corresponding to that posi-.

tion in which it is placed by movement of the thermostat to its hotposition, relatively stationary abutment means, and latching means onsaid armature, failure of said electromagnet to become energized duringthe interval that said thermostat is in its hot position resulting, uponreturn oi said thermostat to itscold position, in movement of saidelement in a direction tending to return said burner motor switch andsaid single-pole double-throw switch to their original positions, saidlast-named movement being interrupted, however, by engagement of saidlatching means with said abutment means, with said element in suchposition that the burner switch is open and the movable contact of thesingle-pole double-throw switch is in contact with neither of its fixedcontacts.

aforesaid electrical heater and thereby be caused to move to its hotposition, means mechanically coupling said thermostat and said elementin such manner that as said thermostat moves to its hot position, itactuates said element to close said burner motor switch to empower theburner motor and to move the movable contact of the single-poledouble-throw switch from the stationary contact of the aforesaid firstbranch circult to the stationary contact of the aforesaid second branchcircuit, thereby to deenergize the electrical heater and to place theelectromagnet in condition to be energized, said thermostat thereuponcommencing to cool, an armature mechanically coupled to said element andpositioned to be magnetically responsive to the aforesaid electromagnetwhen said electromagnet is energized and when said armature is in aposition corresponding to the hot position oi said thermostat, saidelectromagnet normally being energized during the interval that saidthermostat is in its hot position by said combustion control mov-' ingto close the aforesaid second branch circuit, said electromagnet duringits energization thereby maintaining said element in aswitch-controlling position corresponding to that position in which itis placed by movement of the thermostat to its hot position, relativelystationary abutment means, and latching means on said armature, failureof said electromagnet to become energized during the interval that saidthermostat is in its hot position resulting, upon return of saidthermostat to its cold position, in movement of said element in adirection tending to return said burner motor switch and saidsingle-pole double-throw switch to their original positions, saidlast-named movement being interrupted, however, by engagement of saidlatching means with said abutment means, with said element in suchposition that the burner switch is open and the movable conta'ctof thesingle-pole doublethrow switch is in contact with neither of its fixedcontacts, said latching means being composed at least in part ofmagnetically responsive material and thereby being magneticallyresponsive to magnetic flux in said armature induced by the energizedelectromagnet, whereby said 12. A burner control system comprising anoil mlatphmg means are rendered noncwpemtive burner motor, a powercircuit including said motor and an electrical switch in said powercircuit having a movable contact; a control circuit including a sourceof power, a room thermostat which closes upon demand for heat connectedin series therewith, a combustion control in series with the roomthermostat, which combustion control closes a first branch circuit uponattainment of satisfactory combustion at the oil burner and which closesa second branch circuit when satisfactory combustion is not taking placeat the oil burner, said first branch circuit including an electricalheater and said second branch circult including an electromagnet, thereturn lead of the heater being connected to one stationary contact of asingle-pole double-throw electrical switch while the return lead of theelectromagnet is connected to the other stationary contact of saidsingle-pole double-throw switch, the movable contact of said single-poledouble-throw switch being connected to the aforesaid control circuitpower source; an element mechanically coupled to the movable contacts ofboth said burner motor switch and said single-pole doublethrow switchfor actuating-the same, a thermostat having relatively hot and coldpositions and located in such manner as to be heated by the with saidabutment means when said electromagnet is energized.

13. A burner control system as set forth in claim 11, in which anignition circuit for the burner is. also provided, said ignition circuitincluding a power source, an ignition device, and an electrical switchhaving a movable contact which is mechanically coupled to the aforesaidelement for movement therewith in the same phase relationship as themovement of the movable contact of the burner motor switch.

14. A burner control system as set forth in claim 11 in which a by-passcircuit is provided in the aforesaid controbcircuit around thecombustion control and the single-pole double-throw switch, the by-passcircuit including a manually operable switch, whereby, upon manualoperation of said switch, said electromagnet is enersized regardless ofthe positions of said combustion control and said single-poledouble-throw switch.

15. A burner control system as set forth in claim 12 in which a bypasscircuit is provided in the aforesaid control circuit around thecombustion control and the single-pole double-throw switch, the by-passcircuit including a manually operable switch, whereby, upon manualoperation tion of said switch, said ciectromagnet is ener-n gizedregardless of the positions of said combustion control and saidsingle-pole double-throw switch, said by-pass circuit therebyfunctioning upon manual actuation thereof to relieve the lockedcondition brought about by engagement of said latching means with saidabutment means.

WILLIAM J. MCGOLDRICK.

